Method of manufacturing wiring substrate, and wiring substrate

Abstract

The method of manufacturing a wiring substrate comprises the steps of: performing a pattern exposure of a resin layer containing photocatalyst particles, in a shape of a desired wiring pattern so that the photocatalyst particles are exposed at a surface of the resin layer; performing irradiation of radiation to the resin layer having the exposed photocatalyst particles while the resin layer having the exposed photocatalyst particles is immersed in an aqueous solution of a metallic salt so that a photochemical reduction and precipitating of a metal film onto the exposed photocatalyst particles are performed; and forming a conducting layer on the metal film.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a wiring substrate and a method of manufacturing a wiring substrate, and more particularly, to a wiring substrate and a method of manufacturing a wiring substrate where the adhesion between a resin layer forming a supporting substrate and a conductive layer forming a wiring conductor is improved without using harmful substances, and a high-density arrangement of very fine wires can be achieved. [0003] 2. Description of the Related Art [0004] In recent years, there has been a tendency for the various electronic components which are used in electronic devices to be integrated at higher density, in accordance with reductions in the weight and size of these electronic devices. In response to this, the wiring patterns of the wiring substrate on which the various electronic components are mounted is formed to higher density, and very fine dimensions of the order of approximately 10 μm, for...

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Benefits of technology

[0035] According to this aspect of the present invention, a resin layer containing photocatalyst particles is used, and the metal film for forming a conducting layer is precipitated onto the photocatalyst particles exposed at the surface of the resin layer. Therefore, it is possible to make the conducting layer (or the precipitated metal film) adhere densely to the resin layer in such a manner that the undulation generated in the surface of the resin layer by the exposed photocatalyst particles is compensated, and consequently, the bonding surface area between the resin layer and the conducting layer is increased, and an improvement in the adhesion between the resin layer and the conducting layer, in other words, an improvement in the bonding strength, can be expected.

[0036] If a material having a lower thermal conductivity than that of the material used for the conducting layer is contained in the metal film or the photocatalyst particles, then an effect in shielding heat from the resin layer can be expected. Accordingly, even in cases where high-temperature work, such as soldering, is carried out on top of the conducting layer, the effects of the heat caused by this high-temperature work are prevented from reaching the resin layer, which has inferior thermal resistance compared to the conducting layer.

[0037] According to the present invention, it is possible to achieve close and reliable bonding between a resin layer and a conducting layer, without using harmful substances, and hence a high-density arrangement of very fine wires can be achieved by increasing the density of the wiring pattern.

Problems solved by technology

In the method of manufacturing a printed circuit substrate described in Japanese Patent Application Publication No. 2-205388, pad printing, screen printing, and drawing by means of an X-Y plotter with dispenser attachment, are given as embodiments of methods for patterning the coupling agent containing semiconducting photocatalyst powder; however, with these methods, it is difficult to achieve high density of the very fine regions (very fine wires) in terms of accuracy.

Furthermore, the formaldehyde used in the step of forming a copper coating to form a conducting layer is a harmful substance which clearly has a detrimental effect on the natural environment, and therefore, it is not desirable to use such a substance.

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